I try to avoid using these because they are an obvious indication that the food was not entirely made from scratch. To me, I associate bouillon cubes with those cheaper dried soup mixes in pouches, or some cheap hamburger helper type kits. There is actually a soup based called Better Than Bouillon which is much better than the powdered or cubed varieties. The first ingredient on their labels is actual chicken, and there is no MSG in it (though there are compounds similar to MSG in it). Taste wise it's definitely as the name states, better than the powdered stuff, but not quite as good as the boxed stuff like Progresso. It's also quite cost effective too as one jar of it makes the equivalent of 9 cartons of chicken stock, so it's about 1/9th the price of what you are paying for the boxed varieties.
It's pretty versatile what you can do with it too - I rub the beef base on roasts when roasting them, and similarly sometimes rub whole chickens with the chicken base before roasting them for added color and flavor. You can even toss roasted vegetables with it.